Abstract: A load control device for a working tool of a construction vehicle in which a signal detected by a speed detector or a traction force detector is fed back to produce a deviation signal between said signal and a desired signal. A memory unit has stored a desired value of speed or traction force for each acceleration and outputs the desired signal corresponding to an acceleration signal from an acceleration detector. The working tool is moved up or down according to the deviation signal and, through the feedback mechanism, the load applied to the working tool is automatically controlled so as to enable the construction vehicle to work at maximum work efficiency without operator's efforts.

Abstract: In a civil machine comprising a working tool provided on a vehicle with a travelling mechanism and a drive therefor, an automatic control system comprises a stroke detector for detecting the amount of stroke of a lifting cylinder operating to move the working tool up and down, an inclination angle detector for detecting the inclination angle of the vehicle, an arithmetic unit for obtaining data representative of the height of the working tool from the detection signals of the two detectors, and a control for operating the lifting cylinder by using the data to control the position of the working tool with high accuracy.